However, the interim report concluded the crash was not survivable and stated several aircraft returned to Jackson's Aeredrome, where the doomed flight originated from, because of poor weather.

It also stated aircraft communications in the area frequently overlapped on the day of the crash.

PNG’s Civil Aviation Minister Charles Abel at a press conference in Port Moresby said the victims’ families had received the interim report on Tuesday.

“It’s too early to make any determinations ... this report merely states the factual circumstances. Subsequent to this they will come up with the reasons,” he said.

“The government admits it’s been a little bit lax in getting the accident commission established, but as minister I have full government support to change that.”

PNG’s accident investigator, Sid O’Toole, said the investigation would be a “watershed” moment in PNG’s air safety history considering the resources, commitment and assistance from both PNG and Australia.

“It appeared to be a normal flight, the crew were very experienced in the area ... as to the cause, it’s far too early (to speculate),” he said.

Mr O'Toole said enormous amounts of manpower and resources were dedicated to the investigation.

"I would describe it as a watershed and in fact a historical moment in the history of air safety investigation in PNG."

Plagued by underfunding, PNG’s Civil Aviation Authority has failed to properly investigate 19 air crashes since 2000 in which 16 people, including three Australians and three New Zealanders, have died.

Mr Abel thanked the Australian government for its help in the investigation so far.

Australian Defence Force personnel, Australian Federal Police and the Australian Transport Safety Bureau (ATSB) were deployed to the crash scene in difficult terrain in the Owen Stanley range 10km south of Kokoda.

The plane’s electronic and navigation equipment is now in Canberra under ATSB inspection, while the plane’s two engines will be shipped to Canada next month for similar investigations.

The report states at 11.10am the doomed plane reported being at 9,000 feet on descent to Kokoda via the Kokoda Gap.At 11.14am the plane did not respond to a number of calls from authorities or other planes in the area.

A search and rescue alert was called at 11.36am, and when no emergency locator transmitter signals were received another search and rescue phase was declared at 12.25pm.